Ignore Aikido and the Dynamic Sphere! There is attack in Aikido. Just look at some video clips of O'Sensei to see him move off-line and then attack his Uke! I think there is a clip of that on this site.

Interestingly, the Founder, himself, said there is no attack in Aikido. I take it as a kind of "koan" that I`ve yet to figure out.

To the original question, it was Okumura Shihan that asked about the various "sen" and the answer (as I remember it) is that there is only one sen. Again, another koan to figure out.